Pregnancy outcome after treatment for Wilms tumor: a report from the National Wilms Tumor Study Group.

PURPOSE: This study was undertaken to determine the effect, if any, of prior treatment with radiation therapy or chemotherapy for Wilms tumor diagnosed during childhood or adolescence on live births, birthweight, and the frequency of congenital malformations. PATIENTS AND METHODS: We reviewed pregnancy outcomes among survivors of Wilms tumor treated with or without irradiation to the flank or tumor bed on National Wilms Tumor Studies 1, 2, 3, and 4 using a maternal questionnaire and review of both maternal and offspring medical records.
RESULTS: We received reports regarding 427 pregnancies with duration of 20 weeks or longer, including 409 liveborn singletons for whom 309 sets of medical records were reviewed. Malposition of the fetus and early or threatened labor were more frequent among irradiated women. Both were more frequent among women who received higher radiation therapy doses. The offspring of the irradiated female patients were more likely to weigh less than 2,500 g at birth and to be of less than 36 weeks gestation, with both being more frequent after higher doses of radiation. An increased percentage of offspring of irradiated females had one or more congenital malformations.
CONCLUSION: Women who receive flank radiation therapy as part of their treatment for Wilms tumor are at increased risk of fetal malposition and premature labor. The offspring of these women are at risk for low birthweight, premature (< 36 weeks gestation) birth, and the occurrence of congenital malformations. These risks must be considered in the obstetrical management of female survivors of Wilms tumor.